Nonvolatile memory devices that use resistance materials include resistive random access memory (RRAM) devices, magnetic random access memory (MRAM) devices, and phase-change random access memory (PRAM) devices. Nonvolatile memory devices using resistance materials store data using changes in the resistance of a variable-resistance material (in the case of RRAM devices), changes in the resistance of a magnetic tunnel junction (MTJ) film in accordance with the magnetization state of a ferromagnetic material (in the case of MRAM devices), or changes in the state of a phase-change material such as a chalcogenide alloy (in the case of PRAM devices). In contrast, dynamic random access memory (DRAM) devices or flash memory devices store data using electric charges.
A resistive memory cell may include a variable-resistance element disposed between an upper electrode and a lower electrode, and the resistance of the variable-resistance element may vary according to the voltages applied to the respective upper and lower electrodes.